


Strings

by BuffaloWhiskey



Category: Life with Derek
Genre: F/M
Language: English
Status: In-Progress
Published: 2014-08-02
Updated: 2014-08-10
Packaged: 2018-02-10 18:08:43
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 4,914
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2034915
Author URL: https://archiveofourown.org/users/BuffaloWhiskey/pseuds/BuffaloWhiskey
Summary: <blockquote class="userstuff">
              <p>Casey McDonald has had enough. Her step brother, Derek, is always on her nerves and when she catches her boyfriend cheating, it's the final straw. The strange thing is, despite this perfect opportunity for ridicule, Derek seems to want to help her. Is he actually on her side for once or does his plan come with strings attached?</p>
            </blockquote>





	1. Chapter 1

The door handle rattled. She was really upset this morning. Derek liked that. As often as he tried to come up with new ways to irritate Casey, locking her out of the bathroom when she was running late for school always seemed to do the trick.

"Der-ek!" Music to his ears. "Derek open this door right now!" She huffed, before slamming her palm against the wood paneling. Derek decided now was as good a day as any to start flossing. He shuffled through a drawer and came up with a brand new container of floss with a sticker of a little blue bird on it. Casey put stickers on things like her hairbrush and her tube of toothpaste, for the specific reason of keeping her nosey, unhygienic step brother from mistakenly using her stuff.

Derek popped the plastic top open and unraveled a good ten feet of floss. Perfect.

"Der-ek please! I'm going to get George!"

_Shit,_ he thought, _He's already mad at me for spilling a bottle of Coke in The Prince._

Casey had turned on her heel, dead set on telling George to make his son behave, when she heard the door open behind her.

"You rang?" Derek drawled, spinning a Q-tip in his ear. Casey make an unintelligible growl and shouldered past him. "All yours, princess," he laughed as he flicked the Q-tip over his shoulder.

He had made it to his bedroom and was throwing his backpack on when Casey screeched his name again. He was on a roll this morning.

She was holding up the tangle of floss when he strode past the door. Responding to the angry, pinched look on her face, he said "Gotta keep this smile looking pearly white for the ladies!" He raised his hands in mock surrender, shrugged, and slipped around the corner.

Casey watched his backpack disappear from the hallway and threw the minty smelling tangle onto the ground. She was furious. Today was the one month anniversary of her relationship with Michael, a down-to-earth soccer player who devoted most of his practice time to working on school assignments. Consequently, he spent game time riding the bench, but his devotion to grades was what had attracted Casey to him.

"Casey? Are you okay?" Liz's concerned face poked out of her bedroom. Casey looked like she was about to snap and Liz didn't want to be within the range of her hysterics.

"I had a poem and everything!" Casey was gathering the mess of floss into a ball that she shoved into the garbage can.

Liz knew she was talking about the anniversary. Her older sister had been awake well into the night crumpling up unfavorable stanzas and rewriting them. "Just give it to him after school," she suggested.

Casey daintily picked up the Q-tip between thumb and pointer finger and added it to the trash. "We were going to meet at 7:47, which was the exact time I bumped into him in the hallway when we first met." She leaned against the sink and stared dreamily up at the ceiling.

Liz rolled her eyes so hard it almost hurt. She marched up to Casey and snapped her fingers in her face, "You're not going to be able to meet him at all if you're in detention! Hurry up!"

Casey's eyes widened and she grinned at Liz, "You're a genius!" Her sister looked at the fingers she had just snapped, which were still in Casey's face, and back at her seemingly delirious sister. Casey laughed at the question in Liz's face and excitedly continued, "I'll text him and tell him I got detention, so the anniversary meeting's off. Then, after school, when I'm supposedly in detention, he'll go to his car to leave and I'll be waiting there to surprise him!" She spun around and started pulling her hair into a ponytail while adding, "I can do my makeup during lunchtime."

Liz, deciding she was already too far invested in this idea to notice her little sister, shook her head and left the bathroom.

 

\-------------------------------------------------------------

 

Derek leaned against his locker and eyed a pretty blonde as she sashayed past. He grinned at her and winked at her friend, who responded with, "Hi Derek," and a shy giggle.

_Too easy,_ he thought, watching the girls whisper to each other as his eyes traveled down to the backs of their jeans.

His view was interrupted by a short girl with wide eyes, "Have you seen Casey?" She asked.

Derek mentally shook his thoughts from the way their jeans had been just a little too tight. "Emily," he greeted Casey's friend without much enthusiasm. _What is she, her keeper?_ "Your gal pal was running behind this morning."

Emily's eyes scrutinized his, "No doubt because of you," she said.

Derek grinned his winning Venturi smile, "Either way, Em, I wouldn't wait up if I were you," he slipped around her and strode in the direction of those perfect asses. Which, he had to remind himself, were attached to a pair of girls.

Emily looked down at her phone again. No _One_   _New Text Message_ notification had appeared. Casey had told her every little detail about her anniversary. Her best friend had called her four times, waking her up in the middle of the night, to read her poem revisions. Emily had responded with a sleepy, "Sounds great, Case," every time and promptly threw her head back down onto her pillow. Casey would not miss this meeting.

She looked over at Michael, looking bored next to the water fountains with a pink rose in his hand. He wandered across the hallway and stared noncommittally at a poster attempting to draw attention to the new lunch menu. Emily watched him pull his phone out of his pocket and reply to a message. He took a last look at the rose, threw it in the trash, and walked off.

Emily didn't have time to react because the bell rang.  _I'll talk to Miss No Show during lunch,_ she decided as she rushed off to her first class.

Being conveniently late to class, as he usually was, Derek had witnessed Michael's let down. He realized Casey's boyfriend was upset because of him, and he smirked, before catching himself. Why would he want his step sister's relationship to hit a bumpy road? The guy was awful with a soccer ball, yes, but he had kept Casey out of his hair for about a month. Now that he thought about it, the only time he really actually saw Casey was in the mornings before school. That bugged him. _Probably just because I miss annoying the crap out of her all day,_ he chuckled to himself as he moved down the hall. _Probably._

 

\---------------------------------------------------------------------

 

Casey lifted the bun on her cheeseburger and poked at the meat with a spork. It did not look appetizing, and besides, she was too nervous that something might go awry with her surprise this afternoon. She kept scanning the cafeteria for Michael. She was an awful liar and she really didn't want to spoil their anniversary with a stuttered half-truth about detention.

She had barely made it to school on time. She had slipped into her first period class that she shared with Derek just as the bell shrilled. He had received plenty of unhappy looks from her but countered them with "Yeah but did you get in trouble?" as he butted in front of her on the way out of the classroom.

He loved this. She knew he did. He absolutely could not get enough of her scowls and complaints at his expense. He kept his step sister hanging, just wondering what menace he had cooked up for her next. _Life would be pretty boring without him,_ she had to admit.

"Hey there, Space Case," Derek slid into the seat across from her.

"Speak of the devil," Casey mumbled, stabbing the spork into her burger. She fixed a prim smile on her face and looked up at the mischievous sparkle in his brown eyes. Michael had brown eyes, too. But they weren't so deep, and has lashes weren't long like Derek's.

"What did you call me?" He asked, grinning.

"Nothing," She shook her head and looked back down at her tray. Her anxiety over Michael was just making her see him in strange places. Her step brother, of all people! "Never mind."

Derek continued, "No, no. I heard you. You don't usually dish out such high praise. Did I do something to upset you?" He added nonchalantly.

Casey glared at him, her eyebrows arching angrily over her blue eyes. She hadn't put on any makeup, Derek noticed.

"Go away, I'm not in the mood to deal with you," she hissed through clenched teeth.

"Oh, 'deal with' me?" Derek laughed. He hadn't intended to make it sound like an innuendo, but it had the desired effect.

She broke eye contact and threw the spork at him. He ducked his head to the left and easily dodged the plastic projectile. She was too predictable sometimes.

"I'm not interrupting anything, am I?" The step siblings looked up from their tension filled argument to see Michael, standing awkwardly to the side of the table, his hand scratching the back of his head.

"Not at all!" Casey grinned at him, then turned to Derek, "Right, Derek?"

Derek pushed his chair back, "All yours, dude," throwing a wink at Casey, he sauntered off.

Michael watched Casey's face go from faux pleasantry to very puzzled, "What's wrong, Babe?"

Casey hated when he called her that. It just didn't sound right to her. She ignored it, though, throwing the smile back onto her features, "Nothing, just Derek being... Derek," she let out a small chuckle for Michael's benefit. If it had sounded forced, he didn't seem to notice, delving into his lunch instead. Casey wasn't hungry, she was still wondering what that wink was supposed to mean.

 

\---------------------------------------------------------

 

The last bell of the day rang and Casey gathered her notebook and pencil. Shoving them into her oversized purse, she made a beeline for the ladies room to give her makeup a final once-over. The detention fib went well, Michael hadn't suspected a thing. Granted, he had been enjoying his sandwich with what must have been only slightly less enthusiasm than he might have had in the bedroom. She was surprised he didn't moan into that turkey club. _Well,_ She thought guiltily as she layered on a fruity tasting chapstick, _I lied only so I could surprise him. That doesn't make me a bad person._

Pursing her lips together in the mirror and opening them with a little _pop,_ Casey made her way to the parking lot.

Derek leaned against the chipping paint of The Prince, chatting up the two girls with the asses from that morning. A well practiced exaggeration about the horsepower under the hood rolled off his tongue. They believed him easily, partly because they knew nothing about cars and partly because he had a way with words. Derek could slide any lie into a conversation as easily as a knife into warm butter.

"So when are you going to take us for a ride?" The taller blonde blinked up at him. Her friend, also blonde, just twirled a strand of hair around her middle finger and stared at the old clunker in awe.

_You're already being taken for a ride,_ Derek chuckled internally at his joke. There was no challenge at all with these girls. He could probably have them both in bed by the end of the week, they definitely seemed like the type. _Two at a time, that sounds like fun._

"How does this weekend sound?" He said in response to the previous question. The girls grinned. No lines, no games. Straight to the point. Derek was charming enough to pull it off. He exchanged numbers, entering their names in his phone and promptly forgetting them. It didn't matter, he knew they would both text him before the day was over. That was how it always worked.

The girls flounced away, chatting excitedly, as his step sister strolled by. "Two at a time?" Casey said with false incredulity, "They must not have heard about your reputation, Der."

"The one where I'm incredible in bed?" Derek smirked.

"The one where you sleep with a girl and never talk to her again."

He laughed "Ah the classic 'fuck and flee.' "

Casey scrunched up her face "Der-ek! Enough with the cussing, have some decorum!" She looked like she had sucked on a lemon.

"What in the shit," He raised his eyebrows for that one word, "Does that even mean?" He shifted his weight off of The Prince and turned around to unlock the door.

Derek knew what it meant, but irritating her was just too much fun. He didn't have to see her to know what the look on her face was. He glanced up from twisting the key in the lock and saw Michael's car, six spaces down. Casey was too upset with her step brother to notice, but Michael was standing between the legs of a skinny brunette perched on the trunk of his green Chevy Cavalier. He had his hands on either side of her belt and his mouth all over hers.

Derek's first thought was to prevent a dramatic performance from Casey in the middle of the school parking lot. He grabbed her shoulders and spun her around, forcing her back against the car so she would be facing him. Not Michael.

She tried to slap him but he pinned her arms down at her sides, leaving Casey wondering when he had gotten so strong. She looked up from his hands above her elbows to yell at him when she found his face _right there._

He opened his mouth, "Casey, don't freak out." Had he always had faint freckles on his nose?

Coming to the realization that this was _Derek,_ she trilled, "You will see the mother of all freak outs if you do not let me go this instant!"

He tried to get her to understand before she saw it for herself, "Case, just let me-"

"This instant!"

"Okay, it's your funeral," Derek released her and stepped away, hands up as if he was trying to calm a wild animal.

Casey glared at him, _What was the point of that?!_ She wondered angrily. Deciding to continue with her plan to surprise her boyfriend, she huffed at Derek and marched around The Prince, away from the frustrated look he gave her. She saw the familiar green hood of Michael's car, just a few spaces off.

She squared her shoulders, tucked an errant strand of hair behind her ear, and fixed an easy smile on her face. That was when she saw them.

No words. There were no words for how insanely betrayed she felt. The smile dropped and her feet stopped moving. Her boyfriend's mouth moved in the hollow of another girl's neck while her fingers combed through his hair. In the middle of the school parking lot, no less. Casey was set on giving him a berating lecture he'd never forget when a hand gripped her shoulder.

It was Derek. "Casey, don't."

She didn't look away from the double-crossing couple, "And why shouldn't I?"

"He's not worth it."

"He deserves every single word I'm about to say to him, the _fraud!"_ She tried to jerk her shoulder out from under his palm.

Derek simply held on and leaned forward, talking directly into her ear, "He deserves to have his fat little ego shattered into a million pieces. There are much more effective ways to do that."

Casey slowly turned towards her step brother, noticing his sullen look, his eyes locked on Michael. For a second, she wondered why he even cared - he liked seeing her suffer - but her curiosity got the better of her and she moved closer to Derek, "How?"


	2. Chapter 2

Derek's glare didn't leave Michael, just as his lips never strayed from their spot near her ear. "Let's get out of here," he said, in the same grim voice he had been using seconds before.

"Derek, how?" Casey repeated, his cheek less than inches from the side of her face. She would have blushed if she weren't so curious about his plan.

"We need to go," he turned so his nose brushed the top of her ear, "Now." His voice had taken on a violent edge.

Casey's curiosity was abandoned. His tone of voice made her shiver. Or was it his breath tickling her ear? She let him usher her into the passenger side of The Prince and settled onto the cracked leather seat. Derek slid in the other side, wrenching the car into gear. He backed out of the parking spot and drove in the opposite direction of the Cavalier and it's offending occupants, only bothering to clip his seatbelt over his shoulder after they had left the lot.

Neither of them spoke as he pushed the speed limit to the outskirts of town. Casey didn't ask where he was going, instead, she watched him from the corner of her eye and let him drive, the angry look on his face fading as the miles passed. She thought about Michael, and how quickly her affectionate feelings towards him turned sour. She couldn't understand how he could do this to her, why anyone would want to do something like that.

Derek was starting to relax into the rhythm of the road, with its curves and hills, when he heard Casey sniffle quietly. She was crying, and, after what had happened, he really didn't blame her. Her sobs were getting heavier when he gently guided the vehicle on to the gravel on the side of the road.

Wordlessly, he pressed the button to release his seatbelt and reached an arm out to his simpering step sister. She didn't protest as he wrapped her in an embrace and held her while she sobbed.

Even after her tears had turned to hiccups and then to quiet breathing, he didn't let go. He didn't know why. He hadn't been planning on comforting Casey like this, but as soon as The Prince had crunched to a stop on the gravel next to an open field, his body decided to act of its own accord and he did nothing to stop it.

Derek's arm had fallen asleep where Casey's head rested on it when she finally broke the silence. "Derek?" She asked quietly, "What's your plan?"

Derek's face scrunched up in confusion, "What?"

"Your plan," Casey pulled herself out of his arms and turned to face him, wiping at her makeup, smudged from crying, "To get revenge on Michael." She noticed him stiffen at the mention of Michael's name. The movement was barely noticeable, but she had been watching. Why did this situation affect him so much?

He noticed her eyes were bright from crying, ignored the mascara staining her cheeks. He hadn't been thinking about revenge, only about comforting Casey. But revenge was Derek Venturi's forte, and he immediately snapped into his trickster mode, the shift evident in his eyes. His pupils lost the confused pallor from a moment ago and started twinkling with mischief. "Michael," he began, "Deserves worse than your average payback. I'm thinking traumatic public humiliation with a little heartbreak thrown in." He emphasized by holding his thumb and index finger an inch apart, arm tingling as it came back to life.

Casey looked excited. Here was Derek in his natural element, envisioning an awful prank. For once, she wasn't about to be on the receiving end.

As she listened, a slight tickle of wariness niggled in the back of her brain, and she reminded herself not to let her guard down.

 

\---------------------------------------------------------------

 

 By the time the step siblings pulled into the driveway of their house, the sky was turning to the murky blue of dusk and the chirping of the crickets in the yard was in full swing. Inside, Nora stood in the doorway between the kitchen and the dining room, nervously pulling at her fingers.

"What's the big deal?" Edwin, from his seat in front of the TV, asked. "Derek's never home on time."

"I know, but it's not like Casey to be out this late. What if she was walking home and she got mugged?"

The young boy rolled his eyes, "Highly unlikely, Nora."

She ignored her step son, "I should have bought her a can of pepper spray. You know, the kind you can just clip onto your keychain?" Edwin was unresponsive, his program coming back onto the TV as the commercials ended. He barely glanced up when the door swung open.

Nora was gearing up to ream her daughter out for not calling when she noticed Casey's smudged makeup. Casey had attempted to wipe it off on the long drive home, not fully removing the evidence of her tears. Nora rushed up to her, motherly concern in her eyes. "What happened?" She asked. She shot a glare at Derek who walked inside behind Casey.

He held up his hands in surrender, "Wasn't me this time," and turned and jogged to the kitchen. Derek hadn't eaten since lunch time and his stomach was growling at him for food. Plus he couldn't handle another bawling session.

Derek dodged the countertop and dove into the fridge. It was almost empty. He pushed aside a bottle of apple juice and found half of a sub sandwich with Edwin's name scribbled on the wrapper. Sweet. It was gone in four bites and he moved around the island to eavesdrop, another Derek specialty.

"You haven't broken up with him?" Nora sounded incredulous. "Why in heaven's name not?! After what he did..."

Casey picked up where she had trailed off, "I'm going to get revenge." Derek cringed. You don't tell your parents about those kind of plans.

Nora balked. "Revenge? Isn't that a little over the top, honey?"

"I know, you want me to take the high road. Forgive and forget. But this isn't something I can just forget about, Mom." Her voice shook a little and Derek could tell she was about to start tearing up.

"Just key his car," Edwin piped in.

Nora glared at him and Derek took the moment of distraction as an opportunity, pinching the underside of Casey's arm as he made for the stairs.

"Ow!" It was a sensitive spot and it had the desired effect. She chased him to the second floor and into his bedroom. Where she lost him. She turned around and scanned the messy room when he stepped out from behind his door and closed it, shutting her inside. "Der-ek!"

He ignored her. "Rule number one of pranking, Case. The parents aren't supposed to find out until _after_ the deed is done."

"Oh," She said, pushing a rumpled hoodie away from her with her foot.

"Or better yet, not at all," He continued, moving from the door to sit on the edge of his bed. He pulled his sneakers off without bothering to unlace them. "Got it?"

"I got it," Casey rolled her eyes.

"Good," He reached back and grabbed his shirt between his shoulder blades, pulling it up over his head, "Now get out, I'm going to sleep."

She glared at his hair, even more tousled from the act of undressing. "Don't you mean, 'Get out, _please?'_ " She crossed her arms.

He glanced up from working on his belt. "You don't wanna leave? Suit yourself," he shrugged, pulling it out of the belt loops on his jeans.

Casey realized she wasn't going to get a single polite comment from her step brother and turned away with a huff, promptly tripping over the hoodie she had so carefully moved away earlier.

"Ha!" Derek barked. "Go to bed, Klutzilla."

"You are incorrigible!"

"You love it."

She averted her eyes as his jeans hit the floor near her hand and hurried out of his room, shooting, "In your dreams!" Over her shoulder. Derek chuckled and rolled into his unmade bed, his head finding the same spot on his pillow from the night before.

 

\----------------------------------------------------------

 

Casey locked the bathroom door and started her nightly routine to get ready for bed. She showered, brushed her teeth, and gargled mouthwash while putting lotion on her freshly shaved legs. It felt good to wash that mascara off of her cheeks and stand under the hot water as she pictured herself kneeing Michael in the crotch. She wasn't going to, of course. Derek's plan involved Casey pretending everything was peachy keen with her traitorous boyfriend. She wasn't about to let him know that she had caught him. Not yet.

Either way, Casey needed to get rid of this awful mood that Michael's actions had created. She sent a text to Emily asking her what she did when she was feeling down. She didn't really know why, but she didn't want to tell her friend about the revenge plan just yet.

Her phone pinged almost immediately. _First you'd better tell me where you were this morning._

She had forgotten to connect with Emily at lunch. Had her encounter with Derek in the cafeteria really had that much effect on her? It wasn't like Casey to leave her best friend out of the loop. Reading Emily's inquisitive text again, she realized she didn't feel like recounting all the drama.

She sent back one word, _Derek._ It wasn't actually a lie.

 _Say no more._ Came the reply. _Now go blast some happy music and dance around your room._

Casey smiled. Sometimes Emily understood her perfectly. _Thanks, Em. I'll talk to you tomorrow and I promise I'll be on time!_ She added a smiley face and hit send. Pulling her bathrobe tighter around her shoulders, she went to her room to plug her phone in to the wall to charge. She grinned at the good night text that her friend had just sent. She was already feeling better but she wasn't about to knock her best friend's advice so she stuck some headphones in and scrolled through her mp3 player for some upbeat music.

Three songs later, she was bouncing around her room, singing along. _No boy is gonna keep me down,_ she thought. Whether it was the music or the anticipation of Derek's plan, Casey was in a good mood again.

She shook her hair out and flounced her hips, spinning around right into Derek. She reddened, as he looked down at her and laughed.

"How long," She popped her headphones out of her ears, embarrassed, "Have you been standing there?"

"Long enough." He stopped laughing when he noticed her silly polka dotted bathrobe, and the dangerous amount of skin it was showing where it had slid off her shoulder. She was only his step sister, but her half exposed breast was enough to drive any teenage boy nuts.

Still red as a tomato, she scoffed "Don't you know how to knock?"

He straightened up, trying to keep his eyes on her face. It wasn't easy. "I did." She flicked her hair over her shoulder. Derek was half asleep and part of his mind didn't care that they were almost related. Her movement dislodged the brightly colored garment even further and he shifted a little to disguise the slight bulge in his boxers. "You were too busy with The Spice Girls to hear me."

Casey covered her mouth with her hand, effectively obscuring his view of her nipple, "Was I singing too loudly?"

Derek inwardly breathed a sigh of relief as he willed himself to calm down. "I've been to concerts quieter than you," He exaggerated.

"Did I wake anyone else up?" She asked.

"Not that I can tell, but keep it down, Scary Spice."

Her look of embarassment turned to indignation, "For your information, I was listening to Shakira!"

"I couldn't care less," He said as he walked away. He turned around in his doorway, one hand on the knob. "And Case, I don't think Shakira warrants a strip tease," Pointedly nodding at her chest, he shut the door.

Casey turned a shade of red that was even deeper than earlier. She hastily pulled the robe back over her shoulder and scurried into her room, locking the door as she exchanged the fluffy garment for a baggy t-shirt and pajama shorts.

Untucking her meticulously made bed, she snuggled under the covers. Her embarrassment subsided as she thought about how Derek has seen worse. There was the time he pantsed her in algebra class, and the time he snuck in on her taking a shower so he could pour a bucket of ice cold water over the top of the shower curtain and onto her head. Those incidents had left her fuming mad at the time, but now that she thought back on them, she couldn't help but laugh to herself. Derek was... Derek, and underneath the rude, womanizing exterior, he could be a good guy.

 _And when had he started working out?_ She thought, remembering his abs from when he had showed up at her door, too tired to put a shirt on. He had a faint trail of hair leading from his belly button down into the waistband of his boxers, which were slung low on his hips. _Stop!_ She mentally chastised herself, _Stop thinking about Derek!_

It was late, and she was tired. _Who thinks logically at this time of night, anyway?_ Casey buried her face in her pillowcase and slipped off to sleep.


End file.
